In a June 2018 article published in the Journal of Animal Science, researchers studied Eimeria acervulina infection in broiler chickens. In order to better characterize the host response to infection over time, specific research focus was on nitration events in the duodenal epithelial cells (ETCs). Duodenal structural changes and two specific biomarkers: 3′-nitrotyrosine proteins (NTp), which form during increased oxidative stress, and xanthine oxidase (XO), an enzyme that generates superoxide anions (SOA), were evaluated.

E. acervulina is a parasite that causes pathology in the duodenum of chickens. Host cells produce toxic radicals like nitric oxide (NO) and superoxide anions (SOA) that encourage cell turnover and death to combat the infection. This normal response to infection however negatively impacts the nutritional status and growth of broiler chickens. Since the infection lasts for approximately 10 days, a significant portion of pre-market lifespan is affected.

In this study, 49 broiler chickens (male, 21 days old) were randomly assigned to infected (INF) or non-infected (NOI) groups. The INF chickens were treated with 3x105E. acervulina oocysts in 1.0 mL via gavage; NOI chickens were treated with water. Chickens were additionally separated into five sampling groups for days 1, 3, 6, 7 and 10 post-infection.

Results indicated E. acervulina affected both the structural integrity and nitration events in the duodenal ETCs of INF broiler chickens in a time-dependent manner. Both XO and NTp were significantly increased in INF chickens compared to NOI chickens from day 1 post-infection. There was also a steady increase in NTp and XO in INF chickens to a peak concentration on days 6 and 3 post-infection, respectively. The NO concentration was significantly increased at days 6-7 post-infection, returning to comparable levels with NOI chickens by day 10. In INF chickens, duodenal structural integrity was compromised (reduced villus height and epithelial cell thickness, and increased crypt depth) until after day 6, when the authors noted a trend towards improvement, consistent with resolving infection. The authors also reported that a high-level concentration of NTp was found specifically in the ETCs infected with parasites.

The immune response to infection is a double-edged sword. Inflammatory responses by host cells allows for the effective clearance of pathogens. However, this process also damages host cells, which can lead to significant economic losses in the animal production industry. By better characterizing the host response during active infection, the authors’ work may aid future studies to find effective and economically viable ways to maximize recovery and minimize production losses in chickens infected with E. acervulina. It is curious to speculate whether antioxidants or probiotics may have any impact on mitigating the negative effects of the host inflammatory response on duodenal ETCs during active infection.

To view the full article, “Temporal pattern changes in duodenal protein tyrosine nitration events in response to Eimeria acervulina infection in chickens,” visit the Journal of Animal Science.